Getting a divorce increases the risk of developing an alcohol use disorder (AUD) by more than sevenfold for women and almost sixfold for men, new research shows.
The results also predicted that the risk for AUD is elevated for an identical twin getting divorced, but to a much lesser degree, which further suggests that marriage itself – and not genetic or environmental traits - might protect against AUD.
The results are "a wake-up call" for reminding clinicians of the importance of social and psychological factors for alcoholism, lead author Kenneth S. Kendler, MD, professor, Department of Psychiatry, Virginia Commonwealth University, Richmond, told Medscape Medical News.
"This is not just a problem in our genes or in our brain; it's also strongly related to key aspects of the human experience, like having loving and caring relationships," he added.
The study was published online January 20 in the American Journal of Psychiatry.
Keeping Each Other in Check
Research shows that divorced and single people typically drink more than those who are married, but the reason for this is unclear.
"There hasn't been a systematic, large-scale study like this one to give us more insight into the causal nature" of the relationship, said Dr Kendler.
In seeking to clarify this relationship, researchers used several analytic approaches.
From nationwide registers, researchers identified 942,366 individuals born in Sweden between 1960 and 1990 who were married and residing with their spouse in or after 1990 and who had no AUD prior to marriage.
Swedish national databases provide information on hospitalizations and physician visits for such things as alcohol-related pancreatitis and liver disease, as well as legal problems related to alcohol, such as driving while drunk.
The average age at marriage for these persons was about 30 years; AUD onset occurred 8 to 9 years later. During follow-up, 16% of men and 17% of women were divorced, and 1.1% of men and 0.5% of women developed an AUD.
The analysis found that divorce was strongly associated with subsequent onset of AUD in men (hazard ratio [HR], 5.98, 95% confidence interval [CI], 5.65 - 6.33) and in women (HR, 7.29, 95% CI, 6.72 - 7.91).
The researchers looked at three key potential confounders, which on their own substantially predicted AUD risk. These were low parental education, which is a marker for socioeconomic status; a prior drug or criminal problem; and a family history of AUD. Adding these factors only modestly decreased the associations with divorce for both men and women.
The association between divorce and the development of an AUD was much stronger in both men and women if the spouse did not have a lifetime history of AUD.
This, said Dr Kendler, may be because a spouse who drinks "encourages drinking behavior together" and points to the importance of spousal monitoring to control drinking. "In healthy marriage relationships, there's this 'checking phenomenon' where spouses check on one another."
"Golden" Numbers
The researchers aimed to further clarify the association between divorce and AUD by looking at close relatives. They identified pairs of married relatives: full sibling pairs, cousin pairs born within 3 years of each other, and monozygotic twin pairs.
"The problem we face here is that we have two phenomena: we have divorce, and we have subsequent alcohol problems, and we're trying to figure out whether the divorce, or the change in marital status, causes the alcohol problems or whether there are some shared traits that both make you more vulnerable to divorce and make you more vulnerable to drink," said Dr Kendler.
The investigators used the "co-relative" approach, which controls for familial confounding traits and behaviors. This, said Dr Kendler, is "the most novel" aspect of the analysis.
Because monozygotic twins share common genes and childhood environment, the ideal would be to compare these sets of twins in cases in which one of the pair has divorced and the other has not. Because these situations were too rare in the samples, the researchers developed a model in which results across a range of pairs of relatives could be estimated from observed data.
That model showed that the predicted HR for AUD among monozygotic twins was 3.45 in men and 3.62 in women.
These numbers are "sort of golden," because in the absence of a randomized trial, which would be impossible to design in this case, this "human design" provides "about the best control group that you are ever going to find," said Dr Kendler.
The results reveal that in the general population of men, getting divorced increases the risk for AUD six times, but in monozygotic twins, the risk increases only 3.5 times.
"What that's telling you is that a little more than half of that six is probably causal, and the remaining ― about 2.5 HR ― is just a bunch of stuff that makes you more prone to get divorced and a bunch of stuff that makes you more prone to alcohol ― but that part is not causal."
Marriage Is Protective
The bottom line, he said, is that there is something about marriage that protects against alcoholism. "It's not just a result of all these confounds."
The researchers also wanted to know whether the time of the divorce held any relevance. They looked at persons married from the ages of 18 to 25 and those married from the ages of 26 to 32 and found broadly similar patterns.
In both men and women, and in both age groups, the risk for AUD increased substantially in the year of the divorce and remained elevated for many years in those who did not remarry.
Remarrying after being divorced substantially lowered the risk for AUD in both men and women. This, the authors note, provides additional evidence of the protective effect of marriage.
The researchers also investigated the impact of widowhood. Although few persons were widowed (0.24% of men and 0.47% of women), oweing to the relatively young age of the sample, the study found that losing a spouse to death was associated with an increased risk for a subsequent first onset of AUD in both men (HR, 3.85; 95% CI, 2.81 - 5.28) and women (HR, 4.10; 95% CI, 2.98 - 5.64).
Adding the three key confounders attenuated the associations, but less so than in the divorce analysis.
There was a much larger effect on the risk for AUD among widowed persons in cases in which the spouse did not vs did have a history of AUD, but only in women.
The results of this new study are closely related to those of another study carried out by Dr Kendler and colleagues (Am J Psychiatry. 2016; 173:911-918) that showed that going from being single to being married to someone who had no lifetime history of AUD also reduced the risk for AUD.
Better Understanding
Commenting on the findings for Medscape Medical News, Michelle Riba, MD, professor, Department of Psychiatry, associate director of the University of Michigan Comprehensive Depression Center and past president of the American Psychiatric Association, said the study was led by a "thoughtful and fastidious researcher in psychiatric genetics," and its results "help us to understand" the health impact of losing a spouse.
She pointed out that going through a divorce may be just as difficult – maybe even moreso ― than dealing with the death of a spouse.
The study results may have an impact on her own work, said Dr Riba, who oversees a psycho-oncology center that sometimes hosts a hospice discussion group.
"We often wonder whether we should include more talks on alcohol use, and this has made me think about that and whether we're doing enough."
The study did have some limitations, said Dr Riba. For example, the authors did not interview individuals but used only data from registers.
The problem with that, she said, is that the data depend on patients reporting their alcohol use, which is notoriously underrecorded.
Also, the Swedish sample used in the study is likely homogeneous, said Dr Riba. "The results may not be translatable" to other areas, for example, to the United States, in which there are numerous racial and religious groups.
Another problem for Dr Riba was the use of what she called "convenience" cohorts of relatives. "Whenever you do a convenience cohort, you might miss some factors."
The study also does not answer a number of nagging questions. One concerns the degree to which alcohol use during a first marriage "helps inform" a person regarding his or her second marriage.
The authors have disclosed no relevant financial relationships.
Am J Psychiatry. Published online January 20, 2017. Abstract
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Cite this: Marriage a Perfect Prescription to Prevent Alcoholism? - Medscape - Jan 26, 2017.
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